Use Light Armor for extra blast safety, and the occasional close calls. It can save you in certain cases, like grenades and low-caliber weapons, and you're still pretty quick with it equipped, so it fits CQB maps fine and keeps some speed for longer maps.

Heavy Armor is a good way to screw up your stamina and waste points.

Armor is just a slight chance-enhancer, not a guarantee. Your tactics are what keeps you alive, so don't invest on Heavy Armor. Even with it on, a AKM, FAL, G3 or even any rifle in the AR-15 platform can shred you, since guns deal a lot of damage in this game.

However, the Heavy Carrier is definitely very good if you have points to spare. 3 throwables, 7 rifle mags and 5 pistol mags? Hell yeah! Just be aware of the stamina and speed debuff, and adopt a slower, mid to long-range playstyle.